1. Field of the Invention
The present invention relates to a remote copy system including a host computer and a storage apparatus, and to a path setting support method for supporting a network path setting between storage apparatuses which is especially required in copying data between a plurality of storage apparatuses.
2. Description of the Related Art
Along with the development of the information-oriented society, information systems in business enterprises have become increasingly important in these years. As a result, if such information systems go down due to unexpected circumstances such as a natural disaster, terrorism, and hacking, a loss incurred by those businesses has also been more and more increased. Thus, a system of disaster recovery has been widely used as a solution to ensure operation continuity of the information systems even under such circumstances.
The system of disaster recovery is configured to have a primary site for operating an information system at normal times and a secondary site for substituting the primary site at emergencies. At normal times, data is copied from the primary site to the secondary site. If operations at the primary site become difficult or impossible, the data copied into the secondary site is used to continue operations of the information system.
As a fundamental technology to realize such a disaster recovery, there have been known a remote copy technology for copying data from a storage apparatus into a remotely-located storage apparatus via a network path created between the storage apparatuses, and a remote copy function using the remote copy technology.
In the remote copy technology, a copy source and a copy destination are generally set by the volume which is a management unit of a storage area in a storage apparatus. Two volumes paired as a copy source arid a copy destination are called a copy pair. A copy pair is grouped by the host computer or by the application, by which the copy pair is managed. A plurality of copy pairs grouped by the host computer or by the application is called a copy group
There are two main types of remote copy technology, namely, a synchronous copy and an asynchronous copy.
In the synchronous copy, upon a write instruction of data from a host computer at a primary site (a primary host) to a storage apparatus at a primary site (a primary storage), the primary storage writes the data in a storage area therein and transmits the data to a storage apparatus at a secondary site (a secondary storage). Then, after a write of the data in a storage area in the secondary storage is completed, the primary storage acknowledges the completion of the write of the data to the primary host. This means that data in the primary storage and that in the secondary storage are always synchronized. Even if the primary site becomes inaccessible due to a disaster or the like, the secondary site can smoothly substitute the primary site without any data loss. The synchronous copy is suitable for a remote copy between relatively short-distanced storage apparatuses (for example, less than 100 km in distance) because the further the distance between the storage apparatuses becomes, the longer the response time from the primary storage to the primary host becomes.
Meanwhile, in the asynchronous copy, upon a write instruction of data from the primary host to the primary storage, the primary storage writes the data in a storage area therein and, after the write of the data therein is completed, acknowledges the completion of the write of the data to the primary host. The primary storage transmits the data to the secondary storage only after data instructed to be written prior to the data of interest but not yet transmitted to the secondary storage, if any, is all transmitted to the secondary storage. This means that there is a lag from the time when the primary host transmits the write instruction of data to the primary storage until the time when the primary storage transmits the data to the secondary storage. Thus, if the primary site becomes inaccessible due to a disaster or the like, the secondary site may have data loss. The asynchronous copy is suitable for a remote copy between relatively long-distanced storage apparatuses (for example, more than 100 km in distance) because the response time from the primary storage to the primary host does not depend on a distance between the storage apparatuses.
There are two types of asynchronous copy, namely, a push type and a pull type. In the push remote copy, a primary storage transmits data to a secondary storage and also controls a guaranteed order of the data or the like, which places a high load on the primary storage. Meanwhile, in the pull remote copy, the secondary storage acquires data from the primary storage and controls a guaranteed order of the data or the like, which lowers a load placed on the primary storage. The pull asynchronous remote copy has been increasingly used so as to reduce a load on the primary storage which keeps operating at normal times.
A 3DC (three data centers) solution has been in widespread use recently which combines a synchronous copy and an asynchronous copy and can prevent problems of both a limited distance in the synchronous copy and a data loss in the asynchronous copy. In the 3DC solution, two secondary sites are deployed at short and long distances from the primary site. A synchronous copy is performed from the primary site to the short-distanced secondary site, and an asynchronous copy, to the long-distanced secondary site. The primary site is substituted by the short-distanced secondary site in case of a localized disaster, and by the long-distanced secondary site in case of a wide-area disaster. This can minimize the data loss. Further, a function of so-called delta re-synchronization has also been provided for automatically starting a remote copy from the short-distanced secondary site to the long-distanced secondary site, upon a switchover of operations from the primary site to the short-distanced secondary site. Note that a system configuration based on the 3DC solution is referred to as a 3DC configuration. A system configuration having one primary site and one secondary site is referred to as a 2DC configuration.
Japanese Laid-Open Patent Application, Publication No. 2005-182130 discloses automatic definition and control of a transmitting route of a remote command in the remote copy technology. US Patent Application, Publication No. 2006/0112245 discloses a technique of coupling, to a host computer, a plurality of storage apparatuses in which one storage apparatus is coupled to other storage apparatuses in multiple stages.
To use a remote copy function between storage apparatuses, a network path is required to be set between the storage apparatuses. The network path typically uses a SAN (Storage Area Network) based on a fiber channel protocol and a SCSI (Small Computer System Interface) command used as a network between a host computer and a storage apparatus. Unlike an ordinary network protocol such as the IP (Internet Protocol), the SAN requires a setting which distinguishes an initiator from which data is transmitted, from a target to which the data is transmitted. The setting is needed for each host or port of a storage so as to give a correct direction to the network path.
Another setting of a network path referred to as a remote path setting is required which previously specifies a pair of an initiator port and a target port for use in a remote copy. This is because an initiator port is also used for making use of an external connection function in which a storage apparatus is connected to another storage apparatus, and a target port is also used for connecting a storage apparatus to a host computer. Also, a direction of a remote path differs according to a copy type (push or pull) used in the remote copy. Further, the remote path is required to be set each of the pairs of storage apparatuses. In a configuration for a 3DC solution, the setting is required to be performed for the pairs of a primary site and a short-distanced site, the pairs of a primary site and a long-distanced site, and the pairs of a short-distanced site and a long-distanced site.
As described above, a remote path setting between storage apparatuses is complicated because the setting varies depending on the copy type and the direction of a remote path between the storage apparatuses. Actually, inappropriate settings have prevented normal operations in such cases as a discovery (a remote scan) from a storage apparatus at a primary site to a storage apparatus at a secondary site, and a copy pair definition. Those problems cannot be efficiently solved even with the technologies as disclosed in Japanese Laid-Open Patent Application, Publication No. 2005-182130 and US Laid-Open Patent Application, Publication No. 2006/0112245.
The present invention has been made in light of the above circumstances and in an attempt to solve the problems by supporting a user in ensuring a remote path setting between storage apparatuses.